The last effort in the U.S. Congress to tackle climate change head-on died in 2010, amid ferocious lobbying by interests who argued it would wreck the economy. That bill would have cut carbon dioxide emissions 3 percent below their 2005 level by 2012.

The actual 2012 figures are now out and in fact, the United States was able to cut its carbon emissions fourfold below the goal of the ill-fated Waxman-Markey legislation, even though the nation’s economy grew 2.8 percent in 2012. A U.S. Energy Information Administration report released Monday showed that U.S. energy-related carbon emissions last year were 5,280 million metric tons, their lowest point since 1994 and 12 percent below the 2007 peak (and about 11.8 percent below the 2005 benchmark year that was used in the Waxman-Markey bill.)

Only the recession year of 2009 saw a larger drop than last year’s carbon emissions drop of 3.8 percent, which was the largest emissions drop in a year with positive GDP. (See related quiz: “What You Don’t Know About Climate Change Science.”)

Part of the decrease was due to electric power stations making the switch from burning carbon-intensive coal to cheaper natural gas, which burns with half of the carbon emissions. But another major factor was a more energy-efficient economy. Overall energy consumption in the United States shrank 2.4 percent even while the economy grew. Vehicle miles traveled in 2012 were flat compared to 2011, while more energy-efficient vehicles are continuing to enter the market, EIA said. (See related story: “Climate Change Action Could Save 500,000 Lives Annually, Study Says.”)

The EIA said that warm weather in the early part of the year also played a role, and as such, “it is difficult to draw conclusions from one year of data.” Still, the agency ended with a positive outlook for the future: “Other factors, such as improvements in vehicle fuel efficiency and increased use of renewable generation, however, could play a continuing role in subsequent years.” (See related interactive map: “Four Ways to Look at Global Carbon Footprints.”)

I've spent more than two decades covering environment, business, climate and policy in Washington, D.C. Previously, I spent four years as senior online energy editor at National Geographic. Prior to that, I spearheaded a project tracking climate change lobbying for the nonprofit, nonpartisan journalism organization The Center for Public Integrity. Before that, I was a senior writer at U.S. ...